Multiple way connection for a plurality of lines



Nov. 24, 1931. D. K. GANNETT 1,832,977

MULTIPLE WAY CONNECTION FOR A PLURALITY OF LINES Filed Aug. 25. 1928 2 Sheets-Shee l F/L'7' I INVENTOR Z1 Gal/anew Z A ORNEY Nov. 24, 1931. D. K. GANNETT MULTIPLE WAY CONNECTION FOR A PLURALITY OF LINES Filed Aug. 25. 1928 2 Sheets-Sheet 2 INVENTOR BY i2 fi.Glli Ut ATTORNEY Patented Nov. 24, 1931 UNITED STATES PATENT OFFICE DANFORTH K. GANNETT, OF JACKSON HEIGITTS, YORK, ASSIGNOB, TO AMERICAN TELEPHONE AND TELEGRAPH COTHPANY, A CORPORATION OF NEW YORK MULTIPLE WAY CONNECTION FOR A PLURALITY OF LINES Application filed August 25, 1928. Serial No. 301,951.

This invention relates to arrangements for establishing a multiple way connection between a plurality of transmission lines. By a multiple way connection is meant an arrangement whereby a plurality of subscribers may be so connected together that speech originating with any subscriber may be heard by all the other subscribers. In other words, by the arrangements of the invention a greater number than two subscribers may all be brought together for purposes of joint conversation.

In the arrangements of the invention repeater circuits are utilized for connecting aplurality of lines together in such a way that each line is in two-way communication with the other lines. A particular feature of the arrangements of the invention is that voicefrequency signaling devices, or other devices, may be connected to the circuit in such a manner that each of said devices receives currents only from a particular line. This minimizes the effect of echoes on the signaling device since when a signal is sent from the terminal of one line to the repeater point, the first echoes from the other two lines ,cannot reach the signaling device. Other objects and features of the invention will appear more fully from the detailed description thereof hereinafter given.

The invention may be more fully understood from the following description, together with the accompanying drawings in the Figures 1 and 2 of which the invention is illustrated. In Fig. 1 is shown an arrangement whereby a multiple way connection may be established between three transmission lines. ment whereby a multiple way connection may be established between a greater number of lines. Similar reference characters have been utilized to denote like parts in both of the figures.

In the arrangements of 1. are shown three lines L L and L between which it is In Fig. 2 is an alternative arrange desired to. establish a multiple connection. These lines will terminate in the hybrid coils 1. and 5 and the balancing networks N N and N respectively. Each hybrid coil angement will be provided with an input ircuit, such as 2, which will. include am lifying arrangements, such as the tube T The side of each of these hybrid coilsvwhich transmits from the line is connected to the input circuits of the amplifying arrangements which transmit into the other hybrid coils. In other words, line L will be connected through hybrid coil 1 and circuits 6 and 7 to the input circuits of amplifiers T and T which in turn transmit into lines L and L Line L will be connected through transformer 4 and circuits 11 and 12 to the input circuits of amplifiers T and T which in turn transmit into lines L and L Line L will be connected through transformer 5 and circuits 14 and 15 to the input circuits of amplifiers T and T which in turn transmit into lines L and L The input transformers 8, 9 and 10 of each amplifier are shown arranged in the form of hybrid coils with connections from two of the line hybrid coils being made to the terminals which 'would ordinarily be line and network.

The series windings of each of these hybrid coils 8, 9 and 10 are connected to the potentiometers P P and P as shown, for adjusting the gain and thence to the grids of the tubes. The mid-points of each of the hybrid coils are connected to a resistance for balancing the potentiometer. It will be seen that this arrangement gives two way communication between all three of the lines.-

lonnected to the sides of the line hybrid coils which transmit from the lines L L and L are the devices X X and X These devices may, for example, be voice operated signaling devices. However, they are so referred to for purposes of illustration only and may be any other desired type of wave responsive device. Due to the conjugate re lationship between the iranehes of each of the hybrid coils 8, 9 and '10, it will be seen that device X can receive only those currents w iich come in over line L or directly or as a second echo. Similarly, 4L2 and X can receive only those currents which come in over lines ii: and L respectively. Accordingly, the three de ices X X and X, are in the most favorable position which it is possible to iobtain with respect to interference from echoes.

Other arrangements may be substituted for the hybrid-input coils 8, 9 and 10 used for connecting the inputs Of the amplifying elements to the proper lines. an alternat ve rranuement shown in t we c cuit diagram of Fig. 2. gement the transformer arrangements 15, 1G and 17 are utilized in place oi the hybrid coils 8, 5) and 10. The transformer arrangements 15, it) and 17 each employ two input ti whose secondary windings are in series and whose prin ary windings are connected "to proper circuits. In series with each secondary winding: will be a relatively high 1, ance, such the resistances R R and it, For example, witn respect to the transformer ar 'ancemcnt 15 the resistance R, will be sulficiently large so that current coming; in over circuit 14% will be so reduced i 1 the secondary winding of the t'ansformer that practi "ally none oi'- such current will. be transmitted to circuit 12. lVhile the circuit of Fig. 2 has been Sl10\ n as arranged for connecting three lines together, it is obvious that the arrangement may be expanded to connect four or more lines together. In each case, the number of amplifying elements will be equal to the number of lines which it is desired to connect together, and with the arrangements of Fig. 2 any number of circuits may be connected to the input of each amplifier.

lVhile the invention has been disclosed as embodied in certain specific arrangements which are deemed desirable, it is understood that it is capable of embodiment in many and other widely "aried forms 'thout depart ing from the spirit of the invention as defined by the appendedclaiins.

\Vhat is claimed is:

1. An arrangement for providing multiple way connection of th 'ee or more transmission lines, comprising av plurality of an'iplifiers inductirely each having its output circuit connected with a certain one of a plurality of circuits each leading; from 1 certain one of said lines, were responsi e oevices in said circuits, and means asso iatei' with any certain one of said amplifiers ti connect to the input thereof, and in con relation with each other, those of said ci' cuits leading: from lines other than that to which the certain amplifier is connected.

2. Three or more transmission lines terminating in hybrid coils, input and output cir- DAN FORTH K. GANNETT. 

